APPLICATION OF UV-C RADIATION FOR SHELF LIFE ENHANCEMENT OF SUGARCANE JUICE
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CAET, OUAT
Abstract
Sugarcane juice generally preserved by conventional heating processing that induces adversely affects the flavour of the juice and imparts jaggery taste. UV-C treatment is a non-thermal treatment, reported to induce minimal quality changes in a fresh produce and is capable of reducing microbial load. Sugarcane juice was extracted from fully mature and fresh sugarcane and filtered to remove the extraneous matter to get a clear filtrate for the study. UV-C treatment was given to sugarcane juice with 2 and 4 mm thickness in three different intensities of 0.90, 1.35 and 1.80 mW/cm2 for 7, 14 and 21 minute exposure time. Different physicochemical parameters such as TSS, titrable acidity, reducing sugar content, colour value, enzymatic activity and microbial load of treated samples were studied. There was undetectable TPC i,e 5 log cycle reduction in the treatments of 1.35mW/cm2 and 1.80 mW/cm2 for 21 min exposure time in the 2 mm thickness of the sugarcane juice. Sugarcane juice treated with UV-C and heating (50˚C, for 2 min) followed by UV-C treatment (1.35mW/cm2, 14 min exposure time, 2 mm sample thickness) were stored in glass bottle under refrigeration condition up to 21 days. The samples were drawn at a regular interval of 7 days and analysed for physico-chemical, microbiological parameters. UV-C with heat treated sample was found to be optimum taking all the parameters into consideration. After the UV-C treatment, there was no significant difference in TSS, reducing sugar, titrable acidity, but significant increase in titrable acidity and reducing sugar and decrease in TSS values were observed during storage in comparison to controlled sample. Reducing sugar increased up to 2.79 % and TSS decreased up to 10.6 %. During storage in UV-C with heat treated sample, there was significantly least increase in TPC. There was undetectable TPC up to 7 days of storage but after 21 days, there was 4 log cycle increase in treated sample. In this sample, there was least increase in PPO activity, and change in colour increased significantly (P<0.05). The combine effect of UV-C with heat treatment could able to store sugarcane juice up to 20 days under refrigerated condition with some compromise in the colour of the juice. Thus the non-thermal UV-C technique can be considered as effective method for inactivation of microbial load as well as inactivation of enzyme to enhance the shelf life of sugarcane juice.